1. Field of the Invention
The present invention relates to a regeneration control system adapted to control regeneration at deceleration of a generator motor provided in an electric car or a hybrid car.
2. Description of the Related Art
Hitherto, as an automobile equipped with this type of a regeneration control system, there has been known a hybrid vehicle in which one of the pairs of front wheels and rear wheels is connected to an engine, while the other is connected to an electric motor, as disclosed in Japanese Unexamined Patent Application Publication No. 2003-63265. In this type of automobile, the electric motor acts as a generator to perform regeneration during a decelerated travel so as to recover traveling energy in the form of electric energy and to store the recovered electric energy in a battery. Except for a decelerated drive mode, the electric motor is driven as necessary by the electric energy stored in the battery.
In this type of automobile, a vehicular behavior during its turn is stabilized by controlling regenerative braking torque on the right wheel and the left wheel, separately, that are driven by the electric motor on the basis of information, such as a steering angle or a yaw rate, while the vehicle is turning.
In recent years, there has been proposed a four-wheel-drive vehicle adapted to perform drive and regeneration of front wheels by a first electric motor connected to the front wheels and to perform drive and regeneration of rear wheels by a second electric motor connected to the rear wheels. In this type of four-wheel-drive vehicle, detailed regeneration control is conducted by allocating a regeneration amount to the front and rear wheels on the basis of vehicular speed and/or the steering angle of a steering wheel, thereby obtaining high energy efficiency.
Even if efforts are made to stabilize the behavior of the vehicle while turning by carrying out the conventional regeneration control as described above, the behavior of the vehicle may be unexpectedly disturbed due to an influence, such as a disturbance. If the behavior of the vehicle is disturbed, then a driver tries to correct the behavior of the vehicle by performing an operation, such as “counter-steering,” in which the driving wheel is steered in the opposite direction from a turning direction.
However, when the driver is performing the operation for correcting the vehicular behavior, the steering angle and the yaw rate considerably change. Further, when detailed regeneration control is carried out in response to the changes in the steering angle and the yaw rate under such a condition in the four-wheel-drive vehicle, the allocation of the regenerative braking to the front and rear wheels also considerably changes as the steering angle and the yaw rate change. This may make it difficult for the driver to perform an operation based on the braking forces of the front and rear wheels that significantly change and may prevent smooth correction of the vehicular behavior.